Dr. Thomas Michalak is looking to expand his woodchuck colony,
an important tool in his research on hepatitis B -- a deadly virus that
has affected at least five per cent of the world's population.

Dr. Michalak, of the Molecular Virology and Hepatology Research
Laboratory at Memorial's Faculty of Medicine, said the woodchuck model
has become a key contributor in his research and is solving some of the
mysteries surrounding hepatitis B.

"Some sub-species of woodchucks, also called groundhogs, which
occur in
eastern U.S., are susceptible to the virus which is very similar to
that causing hepatitis B. The animals develop liver disease, including
hepatocellular carcinoma, that closely mimics human illness induced by
the hepatitis B virus."

In order to continue to make advances in his research, however,
Dr. Michalak would like to expand his woodchuck colony and he wants to
use Canadian woodchucks. He had been using American woodchucks in the past
because the animals were more easily accessible and were proven to carry
the hepatitis virus.

But over the past few years the demand for American woodchucks
has risen
significantly and prices have gone up.

Dr. Michalak's woodchuck colony is one of only a few in the world.
The colony offers a rare opportunity to carry out investigations in the
natural setting of mechanisms underlying hepatitis B pathogenicity and
to assess new methods to treat hepatitis B virus- induced diseases.

The woodchuck model has become the accepted way to test potential
drugs and new preventative methods against hepatitis B and, in some situations,
drugs against HIV - - to a certain degree, the HIV replication strategy
is similar to that of the hepatitis B virus.

Important new information has been generated by Dr. Michalak and
his research team over the past few years. One of his recent findings is
that the majority of people infected with hepatitis B carry small amounts
of the virus even many years after complete clinical recovery from hepatitis.

"The person exposed to the hepatitis B virus can fully recover
from the symptoms, but traces of the virus will remain present in the circulation,
liver and lymphatic system. Our studies in woodchucks not only fully confirmed
this discovery, but also revealed that convalescent animals carry the virus
for life; the persisting virus is infectious to healthy animals and is
transmittable to offspring. Also, importantly, some of the recovered, apparently
healthy animals develop liver cancer within several months after termination
of hepatitis.

"So, we've found there is a hidden infection, detectable by sensitive
nucleic
acid amplification techniques, which follows symptomatic disease, and
which may have very important epidemiological and pathogenic implications.

"These findings imply that there could be a significant hazard
to transplant organs and transfuse blood from individuals who were exposed
to hepatitis B in the past. The organ and blood have to be carefully checked
to see whether the donor was infected with hepatitis B in the past because
the small amounts of the persisting virus could be infectious."

Dr. Michalak added that it would be advisable to carefully screen
all donors using currently available molecular assays in research laboratories;
however, such tests are not yet licensed or are too expensive for individual
blood and organ screening.

While many advances have been made in hepatitis B research, Dr.
Michalak said a lot of work is still needed in order to come up with a
successful drug to treat the illness.

"We are progressing with the understanding of the molecular and
immunological mechanisms of the disease, but at the present time there
is still no treatment able to indicate the established infection. Some
of the drugs being used now are only successful in a small number of people
and they are not eliminating the virus, just temporarily decreasing its
amounts and the disease symptoms."

Dr. Michalak often thinks of the day when a cure is found for
hepatitis B,
but before that can happen, he says, more knowledge is needed.

"I want to understand the virus persistence and why the same virus
induces
various forms of liver disease in different individuals. So, without
understanding why the virus produces chronic infection, it will be difficult
to find a cure."

He added that the woodchuck colony is important in three areas:
basic research, testing of new therapeutic agents, and evaluation of new
prevention methods.

Dr. Michalak started his research on hepatitis B as a medical
student more than 20 years ago, and when he speaks about the subject you
can hear the passion in his voice. He said he will continue to work in
this area of research for as long as he is able to attract appropriate
resources.

"Many researchers who are now working on HIV and hepatitis C used
to work on hepatitis B, but I continue to stay with the disease because
many basic problems remain unsolved and the understanding of the complexity
of virus-host interactions in this isease remains for me very interesting
and exciting.

"It is also very rewarding to see my younger co-investigators,
graduate students, when they become familiar with this important human
disease they start to see how many interesting things need yet to be done
and how their understanding could contribute to our general knowledge of
disease development and viral pathogenicity. Hopefully, some of them could
continue to work in the same area of biomedical research."